1. Field of the Invention
Example embodiments of the present invention relate generally to communications systems, and, more particularly, to wireless communication systems.
2. Description of the Related Art
Conventional wireless communication systems include one or more base stations or base station routers, which may also be referred to as access points, node-Bs or access networks, for providing wireless connectivity to one or more mobile units, which may also be referred to using terms such as user equipment, subscriber equipment, and access terminals. Examples of mobile units include cellular telephones, personal data assistants, smart phones, text messaging devices, laptop/notebook computers, desktop computers and the like. Each base station may provide wireless connectivity to one or more mobile units, such as the mobile units in a geographical area, or cell, associated with the base station. For example, a base station may provide wireless connectivity to mobile units located in a cell according to a Universal Mobile Telecommunication System (UMTS) specification. Alternatively, a base station router may be used to provide wireless connectivity to the mobile units.
Wireless communication systems may provide multicast services to the mobile units in the system. In a multicast transmission, information in the form of packets is provided by a source, such as a multicast server coupled to the wireless communication system, and the packets are replicated so that identical information may be transmitted concurrently to multiple users. Thus, a single server may provide multicast services concurrently to many mobile units. For example, a single multicast server may provide video streaming, interactive game delivery, news clips, and the like concurrently to several mobile units. Users of mobile units typically subscribe to the multicast services and the mobile units then monitor one or more signaling channels to determine when a multicast transmission may occur. When the mobile unit determines that a multicast transmission is available, the mobile unit may establish a communication channel to receive the multicast transmission.
Conventional multicast service providers deliver information to mobile units over a wireless or air interface using dedicated channels (DCHs) associated with each mobile unit. For example, if several mobile units subscribe to a multicast service provided via a base station, then a dedicated channel is established for each mobile unit and the dedicated channels are used to transmit the multicast packets from the base station to the associated mobile units. However, implementing a multicast service using dedicated channels has a number of drawbacks. For example, each mobile unit consumes resources associated with establishing and/or maintaining the dedicated channel. If a new mobile unit begins transmitting, the corresponding rise in the interference level may force the other mobile units to increase their transmission powers and consume additional resources. Thus, resource utilization scales exponentially with the number of mobile units. Consequently, the total number of mobile units that may receive a multicast service is typically limited by the radio resources available to the multicast service. The restrictions on the number of mobile units that may receive a multicast service may translate into a restriction on the number of potential subscribers, which may in turn limit the potential revenue that may be generated by providing multicast services.